Chapter 17 Configuration Files and Parameters

You can specify mysqlbackup options either on the command line or as configuration parameters inside a configuration file. This section describes the use of configuration files.

In general, mysqlbackup follows the mysql style of processing configuration options: [mysqlbackup] and [client] group options are passed as command-line options. Any command-line options that you specify when you run mysqlbackup override the values from the configuration file, and in the case of duplicate options, the last instance takes precedence.

mysqlbackup also reads the following options in the [mysqld] group in the configuration file to detect parameters related to the source repository when it is not connected to mysqld:

• datadir

• innodb_data_home_dir

• innodb_log_group_home_dir

• innodb_undo_directory

• innodb_data_file_path

• innodb_log_files_in_group

• innodb_log_file_size

• innodb_page_size

• innodb_checksum_algorithm

• innodb_undo_tablespaces

• innodb_undo_logs

• innodb_buffer_pool_filename

Options other than the ones listed above should be specified under the [mysqlbackup] or [client] section in the configuration file.

Within mysqlbackup option names, dashes (-) and underscores (_) may be used interchangeably, similar to mysqld parameters that use this same convention (see Using Options on the Command Line in the MySQL Reference Manual for details). The MySQL server's reference manual typically lists the parameter names with underscores, to match the output of the SHOW VARIABLES statement.

Options Files

mysqlbackup reads the location of the MySQL data to be backed up from the following sources (listed in order of priority):

• The connection information from the running database, whenever possible. Thus, in most cases, you can avoid specifying most options on the command line or in a configuration file.

• Parameters you specify on the mysqlbackup command line. You can specify certain options for individual backup jobs this way.

• The MySQL configuration file (by default, my.cnf on Unix and my.ini on Windows). The parameters are searched for first under the [mysqlbackup] group, then under the [client] group. You can put common parameters that apply to most of your backup jobs into the configuration file.

Configuration Files Stored with the Backup Data

Each set of backup data includes a configuration file, backup-my.cnf, containing a minimal set of configuration parameters. The mysqlbackup command generates this file to record the settings that apply to this backup data. Subsequent operations, such as the apply-log process, read options from this file to determine how the backup data is structured.

Example 17.1 Example backup-my.cnf file

Here is an example backup-my.cnf file generated by mysqlbackup:

#
# Generated backup-my.cnf file.
# Auto generated by mysqlbackup program.
#
[mysqld]
innodb_data_file_path=ibdata1:12M:autoextend
innodb_log_file_size=50331648
innodb_log_files_in_group=2
innodb_page_size=16384
innodb_checksum_algorithm=crc32
innodb_buffer_pool_filename=ib_buffer_pool

All paths in the generated backup-my.cnf file point to a single backup directory. For ease of verification and maintenance, you typically store all data for a backup inside a single directory rather than scattered among different directories.

During a backup, the configuration parameters that are required for later stages (such as the restore operation) are recorded in the backup-my.cnf file that is generated in the backup directory. Only the minimally required parameters are stored in backup-my.cnf, to allow you to restore the backup to a different environment without having to make extensive changes to that file. For example, the innodb_data_home_dir and innodb_log_group_home_dir options are omitted from the backup-my.cnf file when their values are the same as the value for backup-dir .